This invention has for its purpose to enable the immediate liberation or in certain cases a delayed liberation of a physical restraint such as that provided by a band or a safety belt. In any event in which it becomes desirable or necessary to leave the place in which the restraint is normally utilized, there will be found a potential application for the device. Although such a device may find use in restraining means applicable to animals or inanimate objects within the interior or on the exterior of moving or static objects, an application which is immediately apparent is that of the well-known safety belt as found in automotive vehicles. For psychological reasons it would appear that often such safety belts are not used owing to the fear that following an accident the user would be unable to free himself. The present device is designed to act automatically to ensure that under certain accidental circumstances such as fire for instance, the restraining safety belt will be immediately severed. Under other circumstances such as shock following collision a certain delay will be imposed to enable the situation to return to normal thereby to avoid contact injury or violent ejection of the safety belt user from a moving vehicle.
Under certain situations it may likewise be desirable to provide for manual actuation of the device and means have also been provided to this effect.